TY - JOUR
T1 - Hydrolytic properties of a β-mannosidase purified from Aspergillus niger
AU - Ademark, Pia
AU - Lundqvist, Jon
AU - Tenkanen, Maija
AU - Torto, Nelson
AU - Stålbrand, Henrik
AU - Tjerneld, Folke
AU - Hägglund, Per
PY - 1999
Y1 - 1999
N2 - A β-mannosidase was purified to homogeneity from the culture filtrate of Aspergillus niger. A specific activity of 500 nkat mg−1 and a 53-fold purification was achieved using ammonium sulfate precipitation, anion-exchange chromatography, and gel filtration. The isolated enzyme has an isoelectric point of 5.0 and appears to be a dimer composed of two 135-kDa subunits. It is a glycoprotein and contains 17% N-linked carbohydrate by weight. Maximal activity was observed at pH 2.4–5.0 and at 70°C. The β-mannosidase hydrolyzed β-1,4-linked manno-oligosaccharides of degree of polymerization (DP) 2–6 and also released mannose from polymeric ivory nut mannan and galactomannan. The Km and Vmax values for p-nitrophenyl-β-d-mannopyranoside were 0.30 mM and 500 nkat mg−1, respectively. Hydrolysis of d-galactose substituted manno-oligosaccharides showed that the β-mannosidase was able to cleave up to, but not beyond, a side group. An internal peptide sequence of 15 amino acids was highly similar to that of an Aspergillus aculeatus β-mannosidase belonging to family 2 of glycosyl hydrolases.
AB - A β-mannosidase was purified to homogeneity from the culture filtrate of Aspergillus niger. A specific activity of 500 nkat mg−1 and a 53-fold purification was achieved using ammonium sulfate precipitation, anion-exchange chromatography, and gel filtration. The isolated enzyme has an isoelectric point of 5.0 and appears to be a dimer composed of two 135-kDa subunits. It is a glycoprotein and contains 17% N-linked carbohydrate by weight. Maximal activity was observed at pH 2.4–5.0 and at 70°C. The β-mannosidase hydrolyzed β-1,4-linked manno-oligosaccharides of degree of polymerization (DP) 2–6 and also released mannose from polymeric ivory nut mannan and galactomannan. The Km and Vmax values for p-nitrophenyl-β-d-mannopyranoside were 0.30 mM and 500 nkat mg−1, respectively. Hydrolysis of d-galactose substituted manno-oligosaccharides showed that the β-mannosidase was able to cleave up to, but not beyond, a side group. An internal peptide sequence of 15 amino acids was highly similar to that of an Aspergillus aculeatus β-mannosidase belonging to family 2 of glycosyl hydrolases.
U2 - 10.1016/S0168-1656(99)00172-8
DO - 10.1016/S0168-1656(99)00172-8
M3 - Article
SN - 0168-1656
VL - 75
SP - 281
EP - 289
JO - Journal of Biotechnology
JF - Journal of Biotechnology
IS - 2-3
ER -